Field of the Invention
The invention relates to a coil configuration having at least one superconducting coil with an associated coil surface and a conductor containing superconducting filaments and being wound essentially onto the coil surface, the conductor having a longitudinal axis, the conductor having a cross section at every point of the longitudinal axis being distended or extended along a distension or transversal axis oriented approximately perpendicular to the coil surface, and the conductor having two ends protruding from the coil.
Such coil configurations are used as essential components in many kinds of superconducting magnets, for instance superconducting magnets for particle accelerators, MRI equipment and magnetic separators.
A detailed description of superconducting magnets is found in the book entitled "Superconducting Magnets" by M. N. Wilson, Oxford University Press, Oxford 1989. That book describes possible coil forms in connection with the fields to be generated (Chapter 3) and examples are shown in FIGS. 3.9 and 3.14. In Chapter 12, the book includes detailed information on forming the conductors that contain the superconducting materials. Typically, those conductors include superconducting filaments in matrices of copper, copper alloys or similar metals (see FIG. 12.8), for instance, and are constructed as one-piece strips or as cables, each having a number of preferably round wires being cabled to one another. Practical information on how to construct superconducting coils for various applications is found in Chapter 13 and examples are shown in FIGS. 13.5-13.9.
Other information on magnets with superconducting coil configurations is found in IEEE Transactions on Nuclear Science Vol. NS-28 (1981) page 3205, where various embodiments for dipole magnets with superconducting coil configurations that include coils stacked on one another and fastened in support structures, are described. Other embodiments of magnets with superconducting coil configurations can be found in an article entitled "Supraleitende Magnete fur HERA [Superconducting Magnets for HERA]", in Physik in unserer Zeit [Physics in Our Time](1985) 16, and in U.S. Pat. No. 4,038,622 and Published European Application No. 0 276 360 A2. Reference may also be made to European Patent No. 0 208 163 B1 for the use of superconducting coil configurations in particle accelerator systems.
Besides the "classical" superconductors, which are understood to mean certain metals, alloys and intermetallic compounds, having transition temperatures which are quite close to the absolute zero temperature point and which are the only kind discussed in the documents cited above, ceramic superconductors which were discovered a few years ago have transition temperatures that under some circumstances are substantially higher (such superconductors are called "high-temperature superconductors"), and find a use in magnets that has already been considered. A detailed description of the ceramic superconductors known at that time is found in Spektrum der Wissenschaft [Science Spectrum] (1990), page 118. The production of conductors that contain such ceramic superconductors is described in German Published, Non-Prosecuted Application DE 37 24 229 A1.
Flattened conductors, that is conductors which have a longitudinal axis and have a cross section which is extended along a transversal axis at every point of the longitudinal axis, are used particularly for forming heavy-duty coil configurations. Information thereon can be found from the documents cited. Such conductors are wound into coils in such a way that at every point of the longitudinal axis the transversal axis is oriented approximately perpendicular to a coil surface that is defined by the shape and disposition of the coil. In particular, the longitudinal axis in the coil extends essentially parallel to the coil surface. When a flattened conductor is used to produce a coil, it is often difficult to extend the ends of the conductor out of the coil. Since the conductor is always oriented with its transversal axis approximately perpendicular to the coil surface, it was previously bent in a plane that contained the longitudinal axis and the transversal axis, in all of the cases in which one end had to be extended approximately away from the coil surface. However, that presents considerable mechanical strains to the structure of the conductor and under some circumstances can mean that voids are created in the structure and/or that superconducting filaments are damaged, and as a result the load capacity for electric current of the conductor would be restricted. As an alternative to bending the conductor, it is known to solder suitably oriented pieces onto the ends. However, that produces solder points on the coil, which under some circumstances are not superconducting, and have a load capacity which should be understood to mean primarily the maximum value of the electric current that can be conducted through the coil, which can likewise be restricted considerably.